**Question:** Rhinitis medicamentosa is caused by excessive use of -

A. Antihistamines
B. Decongestants
C. Corticosteroids
D. Antipsychotics

**Core Concept:**
Rhinitis medicamentosa is a condition characterized by chronic nasal inflammation resulting from prolonged use of topical nasal decongestants. It occurs due to the compensatory vasoconstriction response to the initial decongestant-induced vasodilation, which leads to chronic irritation and inflammation of the nasal mucosa.

**Why the Correct Answer is Right:**
The correct answer is B: Decongestants. Decongestants, such as pseudoephedrine, work by constricting the blood vessels in the nasal mucosa, reducing nasal congestion. Prolonged use, however, results in a rebound vasodilatory response, leading to increased nasal congestion and the development of rhinitis medicamentosa.

**Why Each Wrong Option is Incorrect:**
A. Antihistamines (Option A): These drugs primarily work by blocking histamine receptors, alleviating allergy symptoms. They do not cause the rebound vasodilation seen in decongestants.

C. Corticosteroids (Option C): These drugs are used for anti-inflammatory and immunosuppressive effects but are not directly associated with causing nasal congestion or rhinitis medicamentosa.

D. Antipsychotics (Option D): These drugs primarily treat psychiatric disorders and do not directly cause nasal congestion or the rebound vasodilation seen with decongestants.

**Clinical Pearl:**
It is essential for healthcare professionals to be aware of the potential side effects and rebound phenomena associated with certain medications, such as decongestants, when prescribing or recommending them to patients. Promptly discontinuing the medication can help prevent the development of rhinitis medicamentosa.